Nonsingular Terminal Sliding Mode Control for PMSM Servo System Based on Backlash Compensation and High-order Sliding Mode Observer

In this paper, the permanent magnet synchronous motor (PMSM) servo system with backlash is studied. Since the mechanical transmission of the servo system uses gears, screw rods, on the one hand, the proper backlash can ensure the normal operation of the transmission mechanism; on the other hand, the existence of backlash nonlinearity will reduce the rigidity of the transmission mechanism, affect the tracking performance of the system, and even lead to mechanical resonance. In order to eliminate the influence of the backlash nonlinearity, the modeling and identification of the backlash nonlinearity are introduced, and the influence of the backlash is compensated in the regulator. In addition, in order to reject the possible model deviation and uncertain interference, reduce steady states fluctuations, a high-order sliding mode observer (HOSMO) based nonsingular terminal sliding mode control (NTSMC) is designed. After simulation verification, the compound controller proposed in this paper can effectively reduce the influence of the backlash nonlinearity and improve the position tracking performance of the system.